xref: /linux/net/mac80211/ht.c (revision 9e9f60108423f18a99c9cc93ef7f23490ecc709b)
1 /*
2  * HT handling
3  *
4  * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
5  * Copyright 2002-2005, Instant802 Networks, Inc.
6  * Copyright 2005-2006, Devicescape Software, Inc.
7  * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
8  * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
9  * Copyright 2007-2010, Intel Corporation
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License version 2 as
13  * published by the Free Software Foundation.
14  */
15 
16 #include <linux/ieee80211.h>
17 #include <linux/export.h>
18 #include <net/mac80211.h>
19 #include "ieee80211_i.h"
20 #include "rate.h"
21 
22 static void __check_htcap_disable(struct ieee80211_ht_cap *ht_capa,
23 				  struct ieee80211_ht_cap *ht_capa_mask,
24 				  struct ieee80211_sta_ht_cap *ht_cap,
25 				  u16 flag)
26 {
27 	__le16 le_flag = cpu_to_le16(flag);
28 	if (ht_capa_mask->cap_info & le_flag) {
29 		if (!(ht_capa->cap_info & le_flag))
30 			ht_cap->cap &= ~flag;
31 	}
32 }
33 
34 static void __check_htcap_enable(struct ieee80211_ht_cap *ht_capa,
35 				  struct ieee80211_ht_cap *ht_capa_mask,
36 				  struct ieee80211_sta_ht_cap *ht_cap,
37 				  u16 flag)
38 {
39 	__le16 le_flag = cpu_to_le16(flag);
40 
41 	if ((ht_capa_mask->cap_info & le_flag) &&
42 	    (ht_capa->cap_info & le_flag))
43 		ht_cap->cap |= flag;
44 }
45 
46 void ieee80211_apply_htcap_overrides(struct ieee80211_sub_if_data *sdata,
47 				     struct ieee80211_sta_ht_cap *ht_cap)
48 {
49 	struct ieee80211_ht_cap *ht_capa, *ht_capa_mask;
50 	u8 *scaps, *smask;
51 	int i;
52 
53 	if (!ht_cap->ht_supported)
54 		return;
55 
56 	switch (sdata->vif.type) {
57 	case NL80211_IFTYPE_STATION:
58 		ht_capa = &sdata->u.mgd.ht_capa;
59 		ht_capa_mask = &sdata->u.mgd.ht_capa_mask;
60 		break;
61 	case NL80211_IFTYPE_ADHOC:
62 		ht_capa = &sdata->u.ibss.ht_capa;
63 		ht_capa_mask = &sdata->u.ibss.ht_capa_mask;
64 		break;
65 	default:
66 		WARN_ON_ONCE(1);
67 		return;
68 	}
69 
70 	scaps = (u8 *)(&ht_capa->mcs.rx_mask);
71 	smask = (u8 *)(&ht_capa_mask->mcs.rx_mask);
72 
73 	/* NOTE:  If you add more over-rides here, update register_hw
74 	 * ht_capa_mod_mask logic in main.c as well.
75 	 * And, if this method can ever change ht_cap.ht_supported, fix
76 	 * the check in ieee80211_add_ht_ie.
77 	 */
78 
79 	/* check for HT over-rides, MCS rates first. */
80 	for (i = 0; i < IEEE80211_HT_MCS_MASK_LEN; i++) {
81 		u8 m = smask[i];
82 		ht_cap->mcs.rx_mask[i] &= ~m; /* turn off all masked bits */
83 		/* Add back rates that are supported */
84 		ht_cap->mcs.rx_mask[i] |= (m & scaps[i]);
85 	}
86 
87 	/* Force removal of HT-40 capabilities? */
88 	__check_htcap_disable(ht_capa, ht_capa_mask, ht_cap,
89 			      IEEE80211_HT_CAP_SUP_WIDTH_20_40);
90 	__check_htcap_disable(ht_capa, ht_capa_mask, ht_cap,
91 			      IEEE80211_HT_CAP_SGI_40);
92 
93 	/* Allow user to disable SGI-20 (SGI-40 is handled above) */
94 	__check_htcap_disable(ht_capa, ht_capa_mask, ht_cap,
95 			      IEEE80211_HT_CAP_SGI_20);
96 
97 	/* Allow user to disable the max-AMSDU bit. */
98 	__check_htcap_disable(ht_capa, ht_capa_mask, ht_cap,
99 			      IEEE80211_HT_CAP_MAX_AMSDU);
100 
101 	/* Allow user to disable LDPC */
102 	__check_htcap_disable(ht_capa, ht_capa_mask, ht_cap,
103 			      IEEE80211_HT_CAP_LDPC_CODING);
104 
105 	/* Allow user to enable 40 MHz intolerant bit. */
106 	__check_htcap_enable(ht_capa, ht_capa_mask, ht_cap,
107 			     IEEE80211_HT_CAP_40MHZ_INTOLERANT);
108 
109 	/* Allow user to decrease AMPDU factor */
110 	if (ht_capa_mask->ampdu_params_info &
111 	    IEEE80211_HT_AMPDU_PARM_FACTOR) {
112 		u8 n = ht_capa->ampdu_params_info &
113 		       IEEE80211_HT_AMPDU_PARM_FACTOR;
114 		if (n < ht_cap->ampdu_factor)
115 			ht_cap->ampdu_factor = n;
116 	}
117 
118 	/* Allow the user to increase AMPDU density. */
119 	if (ht_capa_mask->ampdu_params_info &
120 	    IEEE80211_HT_AMPDU_PARM_DENSITY) {
121 		u8 n = (ht_capa->ampdu_params_info &
122 			IEEE80211_HT_AMPDU_PARM_DENSITY)
123 			>> IEEE80211_HT_AMPDU_PARM_DENSITY_SHIFT;
124 		if (n > ht_cap->ampdu_density)
125 			ht_cap->ampdu_density = n;
126 	}
127 }
128 
129 
130 bool ieee80211_ht_cap_ie_to_sta_ht_cap(struct ieee80211_sub_if_data *sdata,
131 				       struct ieee80211_supported_band *sband,
132 				       const struct ieee80211_ht_cap *ht_cap_ie,
133 				       struct sta_info *sta)
134 {
135 	struct ieee80211_sta_ht_cap ht_cap, own_cap;
136 	u8 ampdu_info, tx_mcs_set_cap;
137 	int i, max_tx_streams;
138 	bool changed;
139 	enum ieee80211_sta_rx_bandwidth bw;
140 	enum ieee80211_smps_mode smps_mode;
141 
142 	memset(&ht_cap, 0, sizeof(ht_cap));
143 
144 	if (!ht_cap_ie || !sband->ht_cap.ht_supported)
145 		goto apply;
146 
147 	ht_cap.ht_supported = true;
148 
149 	own_cap = sband->ht_cap;
150 
151 	/*
152 	 * If user has specified capability over-rides, take care
153 	 * of that if the station we're setting up is the AP or TDLS peer that
154 	 * we advertised a restricted capability set to. Override
155 	 * our own capabilities and then use those below.
156 	 */
157 	if (sdata->vif.type == NL80211_IFTYPE_STATION ||
158 	    sdata->vif.type == NL80211_IFTYPE_ADHOC)
159 		ieee80211_apply_htcap_overrides(sdata, &own_cap);
160 
161 	/*
162 	 * The bits listed in this expression should be
163 	 * the same for the peer and us, if the station
164 	 * advertises more then we can't use those thus
165 	 * we mask them out.
166 	 */
167 	ht_cap.cap = le16_to_cpu(ht_cap_ie->cap_info) &
168 		(own_cap.cap | ~(IEEE80211_HT_CAP_LDPC_CODING |
169 				 IEEE80211_HT_CAP_SUP_WIDTH_20_40 |
170 				 IEEE80211_HT_CAP_GRN_FLD |
171 				 IEEE80211_HT_CAP_SGI_20 |
172 				 IEEE80211_HT_CAP_SGI_40 |
173 				 IEEE80211_HT_CAP_DSSSCCK40));
174 
175 	/*
176 	 * The STBC bits are asymmetric -- if we don't have
177 	 * TX then mask out the peer's RX and vice versa.
178 	 */
179 	if (!(own_cap.cap & IEEE80211_HT_CAP_TX_STBC))
180 		ht_cap.cap &= ~IEEE80211_HT_CAP_RX_STBC;
181 	if (!(own_cap.cap & IEEE80211_HT_CAP_RX_STBC))
182 		ht_cap.cap &= ~IEEE80211_HT_CAP_TX_STBC;
183 
184 	ampdu_info = ht_cap_ie->ampdu_params_info;
185 	ht_cap.ampdu_factor =
186 		ampdu_info & IEEE80211_HT_AMPDU_PARM_FACTOR;
187 	ht_cap.ampdu_density =
188 		(ampdu_info & IEEE80211_HT_AMPDU_PARM_DENSITY) >> 2;
189 
190 	/* own MCS TX capabilities */
191 	tx_mcs_set_cap = own_cap.mcs.tx_params;
192 
193 	/* Copy peer MCS TX capabilities, the driver might need them. */
194 	ht_cap.mcs.tx_params = ht_cap_ie->mcs.tx_params;
195 
196 	/* can we TX with MCS rates? */
197 	if (!(tx_mcs_set_cap & IEEE80211_HT_MCS_TX_DEFINED))
198 		goto apply;
199 
200 	/* Counting from 0, therefore +1 */
201 	if (tx_mcs_set_cap & IEEE80211_HT_MCS_TX_RX_DIFF)
202 		max_tx_streams =
203 			((tx_mcs_set_cap & IEEE80211_HT_MCS_TX_MAX_STREAMS_MASK)
204 				>> IEEE80211_HT_MCS_TX_MAX_STREAMS_SHIFT) + 1;
205 	else
206 		max_tx_streams = IEEE80211_HT_MCS_TX_MAX_STREAMS;
207 
208 	/*
209 	 * 802.11n-2009 20.3.5 / 20.6 says:
210 	 * - indices 0 to 7 and 32 are single spatial stream
211 	 * - 8 to 31 are multiple spatial streams using equal modulation
212 	 *   [8..15 for two streams, 16..23 for three and 24..31 for four]
213 	 * - remainder are multiple spatial streams using unequal modulation
214 	 */
215 	for (i = 0; i < max_tx_streams; i++)
216 		ht_cap.mcs.rx_mask[i] =
217 			own_cap.mcs.rx_mask[i] & ht_cap_ie->mcs.rx_mask[i];
218 
219 	if (tx_mcs_set_cap & IEEE80211_HT_MCS_TX_UNEQUAL_MODULATION)
220 		for (i = IEEE80211_HT_MCS_UNEQUAL_MODULATION_START_BYTE;
221 		     i < IEEE80211_HT_MCS_MASK_LEN; i++)
222 			ht_cap.mcs.rx_mask[i] =
223 				own_cap.mcs.rx_mask[i] &
224 					ht_cap_ie->mcs.rx_mask[i];
225 
226 	/* handle MCS rate 32 too */
227 	if (own_cap.mcs.rx_mask[32/8] & ht_cap_ie->mcs.rx_mask[32/8] & 1)
228 		ht_cap.mcs.rx_mask[32/8] |= 1;
229 
230 	/* set Rx highest rate */
231 	ht_cap.mcs.rx_highest = ht_cap_ie->mcs.rx_highest;
232 
233  apply:
234 	changed = memcmp(&sta->sta.ht_cap, &ht_cap, sizeof(ht_cap));
235 
236 	memcpy(&sta->sta.ht_cap, &ht_cap, sizeof(ht_cap));
237 
238 	switch (sdata->vif.bss_conf.chandef.width) {
239 	default:
240 		WARN_ON_ONCE(1);
241 		/* fall through */
242 	case NL80211_CHAN_WIDTH_20_NOHT:
243 	case NL80211_CHAN_WIDTH_20:
244 		bw = IEEE80211_STA_RX_BW_20;
245 		break;
246 	case NL80211_CHAN_WIDTH_40:
247 	case NL80211_CHAN_WIDTH_80:
248 	case NL80211_CHAN_WIDTH_80P80:
249 	case NL80211_CHAN_WIDTH_160:
250 		bw = ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40 ?
251 				IEEE80211_STA_RX_BW_40 : IEEE80211_STA_RX_BW_20;
252 		break;
253 	}
254 
255 	if (bw != sta->sta.bandwidth)
256 		changed = true;
257 	sta->sta.bandwidth = bw;
258 
259 	sta->cur_max_bandwidth =
260 		ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40 ?
261 				IEEE80211_STA_RX_BW_40 : IEEE80211_STA_RX_BW_20;
262 
263 	switch ((ht_cap.cap & IEEE80211_HT_CAP_SM_PS)
264 			>> IEEE80211_HT_CAP_SM_PS_SHIFT) {
265 	case WLAN_HT_CAP_SM_PS_INVALID:
266 	case WLAN_HT_CAP_SM_PS_STATIC:
267 		smps_mode = IEEE80211_SMPS_STATIC;
268 		break;
269 	case WLAN_HT_CAP_SM_PS_DYNAMIC:
270 		smps_mode = IEEE80211_SMPS_DYNAMIC;
271 		break;
272 	case WLAN_HT_CAP_SM_PS_DISABLED:
273 		smps_mode = IEEE80211_SMPS_OFF;
274 		break;
275 	}
276 
277 	if (smps_mode != sta->sta.smps_mode)
278 		changed = true;
279 	sta->sta.smps_mode = smps_mode;
280 
281 	return changed;
282 }
283 
284 void ieee80211_sta_tear_down_BA_sessions(struct sta_info *sta,
285 					 enum ieee80211_agg_stop_reason reason)
286 {
287 	int i;
288 
289 	cancel_work_sync(&sta->ampdu_mlme.work);
290 
291 	for (i = 0; i <  IEEE80211_NUM_TIDS; i++) {
292 		__ieee80211_stop_tx_ba_session(sta, i, reason);
293 		__ieee80211_stop_rx_ba_session(sta, i, WLAN_BACK_RECIPIENT,
294 					       WLAN_REASON_QSTA_LEAVE_QBSS,
295 					       reason != AGG_STOP_DESTROY_STA &&
296 					       reason != AGG_STOP_PEER_REQUEST);
297 	}
298 }
299 
300 void ieee80211_ba_session_work(struct work_struct *work)
301 {
302 	struct sta_info *sta =
303 		container_of(work, struct sta_info, ampdu_mlme.work);
304 	struct tid_ampdu_tx *tid_tx;
305 	int tid;
306 
307 	/*
308 	 * When this flag is set, new sessions should be
309 	 * blocked, and existing sessions will be torn
310 	 * down by the code that set the flag, so this
311 	 * need not run.
312 	 */
313 	if (test_sta_flag(sta, WLAN_STA_BLOCK_BA))
314 		return;
315 
316 	mutex_lock(&sta->ampdu_mlme.mtx);
317 	for (tid = 0; tid < IEEE80211_NUM_TIDS; tid++) {
318 		if (test_and_clear_bit(tid, sta->ampdu_mlme.tid_rx_timer_expired))
319 			___ieee80211_stop_rx_ba_session(
320 				sta, tid, WLAN_BACK_RECIPIENT,
321 				WLAN_REASON_QSTA_TIMEOUT, true);
322 
323 		if (test_and_clear_bit(tid,
324 				       sta->ampdu_mlme.tid_rx_stop_requested))
325 			___ieee80211_stop_rx_ba_session(
326 				sta, tid, WLAN_BACK_RECIPIENT,
327 				WLAN_REASON_UNSPECIFIED, true);
328 
329 		spin_lock_bh(&sta->lock);
330 
331 		tid_tx = sta->ampdu_mlme.tid_start_tx[tid];
332 		if (tid_tx) {
333 			/*
334 			 * Assign it over to the normal tid_tx array
335 			 * where it "goes live".
336 			 */
337 
338 			sta->ampdu_mlme.tid_start_tx[tid] = NULL;
339 			/* could there be a race? */
340 			if (sta->ampdu_mlme.tid_tx[tid])
341 				kfree(tid_tx);
342 			else
343 				ieee80211_assign_tid_tx(sta, tid, tid_tx);
344 			spin_unlock_bh(&sta->lock);
345 
346 			ieee80211_tx_ba_session_handle_start(sta, tid);
347 			continue;
348 		}
349 		spin_unlock_bh(&sta->lock);
350 
351 		tid_tx = rcu_dereference_protected_tid_tx(sta, tid);
352 		if (tid_tx && test_and_clear_bit(HT_AGG_STATE_WANT_STOP,
353 						 &tid_tx->state))
354 			___ieee80211_stop_tx_ba_session(sta, tid,
355 							AGG_STOP_LOCAL_REQUEST);
356 	}
357 	mutex_unlock(&sta->ampdu_mlme.mtx);
358 }
359 
360 void ieee80211_send_delba(struct ieee80211_sub_if_data *sdata,
361 			  const u8 *da, u16 tid,
362 			  u16 initiator, u16 reason_code)
363 {
364 	struct ieee80211_local *local = sdata->local;
365 	struct sk_buff *skb;
366 	struct ieee80211_mgmt *mgmt;
367 	u16 params;
368 
369 	skb = dev_alloc_skb(sizeof(*mgmt) + local->hw.extra_tx_headroom);
370 	if (!skb)
371 		return;
372 
373 	skb_reserve(skb, local->hw.extra_tx_headroom);
374 	mgmt = (struct ieee80211_mgmt *) skb_put(skb, 24);
375 	memset(mgmt, 0, 24);
376 	memcpy(mgmt->da, da, ETH_ALEN);
377 	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
378 	if (sdata->vif.type == NL80211_IFTYPE_AP ||
379 	    sdata->vif.type == NL80211_IFTYPE_AP_VLAN ||
380 	    sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
381 		memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
382 	else if (sdata->vif.type == NL80211_IFTYPE_STATION)
383 		memcpy(mgmt->bssid, sdata->u.mgd.bssid, ETH_ALEN);
384 	else if (sdata->vif.type == NL80211_IFTYPE_ADHOC)
385 		memcpy(mgmt->bssid, sdata->u.ibss.bssid, ETH_ALEN);
386 
387 	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
388 					  IEEE80211_STYPE_ACTION);
389 
390 	skb_put(skb, 1 + sizeof(mgmt->u.action.u.delba));
391 
392 	mgmt->u.action.category = WLAN_CATEGORY_BACK;
393 	mgmt->u.action.u.delba.action_code = WLAN_ACTION_DELBA;
394 	params = (u16)(initiator << 11); 	/* bit 11 initiator */
395 	params |= (u16)(tid << 12); 		/* bit 15:12 TID number */
396 
397 	mgmt->u.action.u.delba.params = cpu_to_le16(params);
398 	mgmt->u.action.u.delba.reason_code = cpu_to_le16(reason_code);
399 
400 	ieee80211_tx_skb(sdata, skb);
401 }
402 
403 void ieee80211_process_delba(struct ieee80211_sub_if_data *sdata,
404 			     struct sta_info *sta,
405 			     struct ieee80211_mgmt *mgmt, size_t len)
406 {
407 	u16 tid, params;
408 	u16 initiator;
409 
410 	params = le16_to_cpu(mgmt->u.action.u.delba.params);
411 	tid = (params & IEEE80211_DELBA_PARAM_TID_MASK) >> 12;
412 	initiator = (params & IEEE80211_DELBA_PARAM_INITIATOR_MASK) >> 11;
413 
414 	ht_dbg_ratelimited(sdata, "delba from %pM (%s) tid %d reason code %d\n",
415 			   mgmt->sa, initiator ? "initiator" : "recipient",
416 			   tid,
417 			   le16_to_cpu(mgmt->u.action.u.delba.reason_code));
418 
419 	if (initiator == WLAN_BACK_INITIATOR)
420 		__ieee80211_stop_rx_ba_session(sta, tid, WLAN_BACK_INITIATOR, 0,
421 					       true);
422 	else
423 		__ieee80211_stop_tx_ba_session(sta, tid, AGG_STOP_PEER_REQUEST);
424 }
425 
426 int ieee80211_send_smps_action(struct ieee80211_sub_if_data *sdata,
427 			       enum ieee80211_smps_mode smps, const u8 *da,
428 			       const u8 *bssid)
429 {
430 	struct ieee80211_local *local = sdata->local;
431 	struct sk_buff *skb;
432 	struct ieee80211_mgmt *action_frame;
433 
434 	/* 27 = header + category + action + smps mode */
435 	skb = dev_alloc_skb(27 + local->hw.extra_tx_headroom);
436 	if (!skb)
437 		return -ENOMEM;
438 
439 	skb_reserve(skb, local->hw.extra_tx_headroom);
440 	action_frame = (void *)skb_put(skb, 27);
441 	memcpy(action_frame->da, da, ETH_ALEN);
442 	memcpy(action_frame->sa, sdata->dev->dev_addr, ETH_ALEN);
443 	memcpy(action_frame->bssid, bssid, ETH_ALEN);
444 	action_frame->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
445 						  IEEE80211_STYPE_ACTION);
446 	action_frame->u.action.category = WLAN_CATEGORY_HT;
447 	action_frame->u.action.u.ht_smps.action = WLAN_HT_ACTION_SMPS;
448 	switch (smps) {
449 	case IEEE80211_SMPS_AUTOMATIC:
450 	case IEEE80211_SMPS_NUM_MODES:
451 		WARN_ON(1);
452 	case IEEE80211_SMPS_OFF:
453 		action_frame->u.action.u.ht_smps.smps_control =
454 				WLAN_HT_SMPS_CONTROL_DISABLED;
455 		break;
456 	case IEEE80211_SMPS_STATIC:
457 		action_frame->u.action.u.ht_smps.smps_control =
458 				WLAN_HT_SMPS_CONTROL_STATIC;
459 		break;
460 	case IEEE80211_SMPS_DYNAMIC:
461 		action_frame->u.action.u.ht_smps.smps_control =
462 				WLAN_HT_SMPS_CONTROL_DYNAMIC;
463 		break;
464 	}
465 
466 	/* we'll do more on status of this frame */
467 	IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_CTL_REQ_TX_STATUS;
468 	ieee80211_tx_skb(sdata, skb);
469 
470 	return 0;
471 }
472 
473 void ieee80211_request_smps_mgd_work(struct work_struct *work)
474 {
475 	struct ieee80211_sub_if_data *sdata =
476 		container_of(work, struct ieee80211_sub_if_data,
477 			     u.mgd.request_smps_work);
478 
479 	sdata_lock(sdata);
480 	__ieee80211_request_smps_mgd(sdata, sdata->u.mgd.driver_smps_mode);
481 	sdata_unlock(sdata);
482 }
483 
484 void ieee80211_request_smps_ap_work(struct work_struct *work)
485 {
486 	struct ieee80211_sub_if_data *sdata =
487 		container_of(work, struct ieee80211_sub_if_data,
488 			     u.ap.request_smps_work);
489 
490 	sdata_lock(sdata);
491 	if (sdata_dereference(sdata->u.ap.beacon, sdata))
492 		__ieee80211_request_smps_ap(sdata,
493 					    sdata->u.ap.driver_smps_mode);
494 	sdata_unlock(sdata);
495 }
496 
497 void ieee80211_request_smps(struct ieee80211_vif *vif,
498 			    enum ieee80211_smps_mode smps_mode)
499 {
500 	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
501 
502 	if (WARN_ON_ONCE(vif->type != NL80211_IFTYPE_STATION &&
503 			 vif->type != NL80211_IFTYPE_AP))
504 		return;
505 
506 	if (vif->type == NL80211_IFTYPE_STATION) {
507 		if (sdata->u.mgd.driver_smps_mode == smps_mode)
508 			return;
509 		sdata->u.mgd.driver_smps_mode = smps_mode;
510 		ieee80211_queue_work(&sdata->local->hw,
511 				     &sdata->u.mgd.request_smps_work);
512 	} else {
513 		/* AUTOMATIC is meaningless in AP mode */
514 		if (WARN_ON_ONCE(smps_mode == IEEE80211_SMPS_AUTOMATIC))
515 			return;
516 		if (sdata->u.ap.driver_smps_mode == smps_mode)
517 			return;
518 		sdata->u.ap.driver_smps_mode = smps_mode;
519 		ieee80211_queue_work(&sdata->local->hw,
520 				     &sdata->u.ap.request_smps_work);
521 	}
522 }
523 /* this might change ... don't want non-open drivers using it */
524 EXPORT_SYMBOL_GPL(ieee80211_request_smps);
525